Fireworks explode over the Olympic Stadium during the opening ceremony of the London 2012 Olympic Games July 27, 2012. [Photo/Xinhua]

LONDON - Britain's Queen Elizabeth declared the London Olympics open after playing a cameo role in a dizzying ceremony designed to highlight the grandeur and eccentricities of the nation that invented modern sport.

Children's voices intertwining from the four corners of her United Kingdom ushered in an exuberant historical pageant of meadows, steel mills and megapixels before an audience of 60,000 in the Olympic Stadium and a probable billion television viewers around the globe.

Many of them gasped at the sight of the 86-year-old queen, marking her Diamond Jubilee this year, putting aside royal reserve in a video where she stepped onto a helicopter with James Bond actor Daniel Craig to be carried aloft from Buckingham Palace.

A film clip showed doubles of her and Bond skydiving towards the stadium and, moments later, she made her entrance in person.

"Great Britain was the cradle of modern sport," International Olympic Committee President Jacques Rogge told reporters. "You invented modern sport in the second half of the 19th century."

To underline the point, Bradley Wiggins, crowned five days earlier as Britain's first winner of the Tour de France and hoping to add more road cycling gold in London, tolled the world's largest tuned bell to begin the ceremony.

David Beckham, the English soccer icon who helped to convince the IOC to grant London the Games, sped down the Thames in a speedboat bearing the Olympic flame on the penultimate leg of a torch relay that inspired many ordinary people around Britain.

And in one moment of simple drama, the stadium fell silent as five giant, incandescent Olympic rings, symbolically forged from British steel mills, were lifted slowly out of the stadium by weather balloons, destined for the stratosphere.

More than 10,000 athletes from 204 countries will compete in 26 sports over 17 days of competition in the only city to have staged the modern Games three times.

Most of them were there for the traditional alphabetical parade of the national teams, not least the athletes from Egypt, Tunisia, Libya and Yemen competing in their first Olympics since their peoples overthrew autocrats in Arab Spring revolutions.

Brunei and Qatar were led in by their countries' first ever female Olympians and so, along with Saudi Arabia, ended their status as the only countries to exclude women from their teams.

Fireworks explode over the Olympic Stadium during the opening ceremony of the London 2012 Olympic Games July 27, 2012. [Photo/Agencies]

The Olympic cauldron is seen alight as fireworks are set off during the opening ceremony of the London 2012 Olympic Games at the Olympic Stadium July 27, 2012.  [Photo/Agencies]